scholarly journals TECHNIQUE AND DEVICE FOR THE EXPERIMENTAL ESTIMATION OF THE ACOUSTIC IMPEDANCE OF VISCOELASTIC MEDIUM

2017 ◽  
Vol 8 (4) ◽  
pp. 314-326 ◽  
Author(s):  
O. V. Murav’eva ◽  
V. V. Murav’ev ◽  
D. V. Zlobin ◽  
O. P. Bogdan ◽  
V. N. Syakterev ◽  
...  
Keyword(s):  
Acoustic Impedance ◽  
Experimental Evaluation ◽  
Piezoelectric Element ◽  
Electric Circuit ◽  
Biological Tissues ◽  
Ultrasonic Waves ◽  
Acoustic Parameters ◽  
Laboratory Equipment ◽  
Viscoelastic Media ◽  
Silicone Sealant

Measuring the characteristics of process fluids allows us to evaluate their quality, biological tissues – to differentiate healthy tissues and tissues with pathologies. Measuring the characteristics of process fluids allows us to evaluate their quality, biological tissues – to differentiate healthy tissues and tissues with pathologies. One of the complex acoustic parameters is the impedance, which allows one to fully evaluate the characteristics of viscoelastic media. Most of impedance methods of measurements require using two or more reference media and the availability of calibrated acoustic transducers. The aim of this work ware introduced a methods and construction for the experimental evaluation of the longitudinal and shear impedance of viscoelastic media based on measuring the parameters of the amplitude-frequency characteristics and calculating the elements of the electric circuit for replacing the piezoelectric element which vibrating in the test medium.The paper introduces a methods and construction of the experimental evaluation of the impedances of viscoelastic media. The suggested methods is allowed measuring longitudinal and shear impedances and determining velocities of longitudinal and transverse ultrasonic waves and the values of the elastic moduli of viscoelastic media, including in various aggregate states. The technique is fairly simple to implement and can be reproduced using simple laboratory equipment.The obtained values of the acoustic impedances of the investigated media are in satisfactory agreement with their reference data. In contrast to the known methods for determining the acoustic impedance, the developed technique allows us to estimate with sufficient accuracy the parameter of the shear impedance of viscoelastic media that is difficult to measure at the frequencies of the megahertz range, which determines the shear modulus of the material and characterizes its resistance to shear deformations. The results of the implementation of the developed technique for the estimation of acoustic parameters for a number of media with zero shear elasticity (alcohol, acetone) and viscoelastic media (glycerin, architectural clay, silicone sealant and glue МР-55 before and after polymerization) are presented.

A Ternary Solution for Independent Acoustic Impedance and Speed of Sound Matching to Biological Tissues

1982 ◽  
Vol 4 (2) ◽  
pp. 163-170 ◽  
Author(s):  
Jonathan Ophir ◽  
Paul Jaeger
Keyword(s):  
Speed Of Sound ◽  
Acoustic Impedance ◽  
Soft Tissues ◽  
Sound Propagation ◽  
Biological Tissues ◽  
Liquid System ◽  
The Body ◽  
Acoustic Parameters ◽  
Wide Range

In applications requiring a liquid which is acoustically well matched to biological tissues, it is often difficult to find a material which is matched well in terms of both the acoustic impedance and speed of sound propagation in it; changing one parameter invariably affects the other. A three component liquid system is described, which allows independent adjustment of these two acoustic parameters over a wide range. This range encompasses the soft tissues of the body. Results of parameter measurements are presented in the form which allows simple determination of the mixture required to match any combination of acoustic impedance and speed of sound propagation over a given range.

scholarly journals A Comparative Study on the Efficiency of CFRP and GFRP in the Improvement of Compressive Strength, Acoustic Impedance and Bracing of Filled and Hollow Concrete Columns in Different Layers and Ages

2016 ◽  
Vol 9 (5) ◽  
pp. 110 ◽  
Author(s):  
Mohammadreza Zarringol ◽  
Mohammadehsan Zarringol
Keyword(s):  
Compressive Strength ◽  
Comparative Study ◽  
Ultimate Strength ◽  
Acoustic Impedance ◽  
Concrete Columns ◽  
Concrete Surface ◽  
Ultrasonic Waves ◽  
Shear Strengthening ◽  
Surface Strength ◽  
Strengthening Method

<p>FRP technique is growing in popularity as a modern strengthening method. When it comes to FRP, concrete surface strength plays a determining role in the bond between FRP and concrete. This paper aims to compare the efficiency of CFRP and GFRP in the improvement of compressive strength, acoustic impedance and bracing of filled and hollow concrete columns in different layers and ages. In doing so, we carried out various tests on 18 samples in the ages of 3, 7, 14, 28, 42 and 90 days. According to the results, the strength of un-braced carbon and glass increased by 19-40% and 8-43% respectively and the strength of braced carbon and glass increased by 17-25% and 10-82% respectively. The compressive strength increased by 66% in one-layer CFRP hollow column, 96% in two-layer CFRP hollow column, 123% in three-layer CFRP hollow column, 36% in one-layer GFRP hollow column, 63% in two-layer GFRP hollow column, 105% in three-layer GFRP hollow column, 71% in one-layer CFRP filled column, 138% in two-layer CFRP filled column, 154% in three-layer CFRP filled column, 45% in one-layer GFRP filled column, 79% in two-layer GFRP filled column, and 144% in three-layer GFRP filled column. The ultimate strength of the beams with flexural-shear strengthening was higher than other beams. Also, the increased percentage of fiber resulted in the increased speed of ultrasonic waves. </p>

Classification of Iron Meteorites with High Frequency Ultrasonic Waves

2019 ◽  
Vol 24 (2) ◽  
pp. 277-284
Author(s):  
Dris El Abassi ◽  
Bouazza Faiz ◽  
Abderrahmane Ibhi ◽  
Idris Aboudaoud
Keyword(s):  
Phase Velocity ◽  
Acoustic Impedance ◽  
Nickel Content ◽  
Normal Incidence ◽  
Ultrasonic Pulse ◽  
Ultrasonic Waves ◽  
Iron Meteorites ◽  
Acoustic Transducer ◽  
Pulse Echo ◽  
Non Destructive

We present the results of an ultrasonic pulse-echo technique and its potential to classify iron meteorites into hexahedrites, octahedrites and ataxites by determining their acoustic impedance and phase velocity. Our technique has been adapted from those used in the field of ultrasonic non-destructive investigation of a variety of materials. The main advantage of our technique is that it does not need any preparation of the meteorites like cutting and etching and therefore is rapid, easy and non-destructive. In essence, a broadband acoustic transducer is used in a monostatic pulse-echo configuration which means that both the transducer and the meteorite sample are located in a water bath and adjusted in the way that the ultrasonic pulse shit the meteorite sample at normal incidence. Then the reflected pulses from the front and rear faces of the meteorite sample are measured with the emitting transducer, digitally recorded and processed to analyze the signal. After Fourier transforming the echoed pulses from the front and the rear face of the meteorite sample, the calculated reflection coefficients yield the phase velocity and the acoustic impedance. Our study investigates a variety of iron meteorites collected in Morocco and other countries and it helps to understand how the nickel content of these meteorites affects the acoustic impedance. It reveals that the acoustic impedance of iron meteorites increases with increasing nickel content, so that a further refinement of our technique might have the potential to classify iron meteorites directly and reliably into hexahedrites, octahedrites and ataxites without destroying them.

Laboratory Experimental Verification of the Effectiveness of Acoustical Treatment of Façade Element Frame Profiles

2016 ◽  
Vol 820 ◽  
pp. 431-436
Author(s):  
Boris Bielek ◽  
Daniel Szabó
Keyword(s):  
Laboratory Experiment ◽  
Experimental Verification ◽  
Acoustic Parameters ◽  
Laboratory Equipment ◽  
Measurement Results

Development of modular transparent elemental façade. Laboratory experimental verification of a façade panel and optimization of its acoustic parameters. Measured samples. Laboratory equipment. Methodology of measurement. Results and conclusions of laboratory experiment.

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